HR: 1340h
AN: V53A-1534    [Abstracts]
TI: Seismic Moment Rate Function Inversions from Very Long Period Signals Associated with Strombolian Eruptions at Mount Erebus, Antarctica
AU: * Lucero, C
EM: xian98@nmt.edu
AF: Department of Mathematics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AU: Aster, R C
EM: aster@ees.nmt.edu
AF: Department of Earth and Environmental Science and Geophysical Research Center, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AU: Borchers, B
EM: borchers@nmt.edu
AF: Department of Earth and Environmental Science and Geophysical Research Center, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AU: Kyle, P
EM: kyle@nmt.edu
AF: Department of Earth and Environmental Science and New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AB: Mount Erebus, Antarctica, shows persistent Strombolian activity, principally in the form of impulsive eruptions of simple and very large (up to 10 m diameter) gas bubbles through its long-lived phonolitic lava lake. Eruptions produce oscillatory near-field very long period (VLP; ~8-20 s period) seismic signals due to processes occurring (seconds) before, during, and (up to several minutes) following the characteristic bubble bursts that mark the onset of short period (>1 Hz) seismoacoustic signals. Coupled broadband seismoacoustic and video analysis shows that this signal is associated with three corresponding component processes: 1) the bubble ascent phase characterized by gas/lava mass transport within the conduit system that can produce a positive or negative vertical rate of momentum change, depending on the event; 2) the eruptive evisceration of the lava lake to a depth of up to 10's of m in the explosive surface decompression of the gas bubble; 3) the refilling and reestablishment gravitational equilibrium within the conduit system. We employ a new method for efficiently solving the inverse problem of finding either independent or proportional moment-tensor element rate functions using three-component near-field seismograms recorded at multiple seismic stations. The method incorporates a frequency-domain deconvolution that, in its most general formulation, solves for six independent moment rate tensor force couple time functions plus a vertical force time function. We present an efficient scheme for solving this problem using conjugate gradient methods and apply it to Erebus VLP signals from the past several years of activity.
UR: http://www.ees.nmt.edu/Geop/Erebus/erebus.html
DE: 7280 Volcano seismology (8419)
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005